Barking Ahead of the Sun

When the Dog Star rises, so does the heat

By J. Alex Knoll

The waning moon rises around 10:30pm at week’s end Friday, with the bright glow of Jupiter trailing just a few degrees behind. By Sunday, the last-quarter moon rises a little before midnight just below the speckling lights of the Pleiades star cluster, which mark the back of Taurus. Ten degrees beneath the moon glares the bull’s red eye, the star Aldebaran, and midway between the two, outlining Taurus’ V-shaped face, are the stars of the Hyades cluster.
The sun now sets before 8pm, revealing Saturn in the southwest, trailed a dozen degrees by equally bright Spica, but by 10pm both have set. Jupiter rises in the east-northeast a bit before midnight and is high overhead by sunrise, a bit after 6:20. Mars, the only other planet visible to the unaided eye, rises around 2:30am and is well situated in the east with the approach of dawn.
In the late-summer depths of August, another planetary light rises in the east as if to herald the coming light of the sun. Sirius, the Dog Star, crests the southeast horizon around 5am, and aside from the moon, Jupiter and Venus, buried behind the sun, is the brightest light in the heavens.
Thousands of years ago, Sirius rose in conjunction with the morning sun during the hottest days of summer, and people attributed the heat to its added glow. While we now know better, the pure brightness of Sirius continues to beguile. Always close to the horizon, the brilliant star is magnified and distorted to dazzling effect as it passes through our own atmosphere, leading to dozens of reports of unidentified flying objects this time of year. Part of the reason Sirius appears so bright is because it is the closest star visible in the Northern Hemisphere, at 8.6 light-years. It is twice as big as our sun, small by stellar standards, and burns nearly twice as hot.